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// SPDX-License-Identifier: GPL-2.0-only
/*
* vivid-rds-gen.c - rds (radio data system) generator support functions.
*
* Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
*/
#include <linux/kernel.h>
#include <linux/ktime.h>
#include <linux/string.h>
#include <linux/videodev2.h>
#include "vivid-rds-gen.h"
static u8 vivid_get_di(const struct vivid_rds_gen *rds, unsigned grp)
{
switch (grp) {
case 0:
return (rds->dyn_pty << 2) | (grp & 3);
case 1:
return (rds->compressed << 2) | (grp & 3);
case 2:
return (rds->art_head << 2) | (grp & 3);
case 3:
return (rds->mono_stereo << 2) | (grp & 3);
}
return 0;
}
/*
* This RDS generator creates 57 RDS groups (one group == four RDS blocks).
* Groups 0-3, 22-25 and 44-47 (spaced 22 groups apart) are filled with a
* standard 0B group containing the PI code and PS name.
*
* Groups 4-19 and 26-41 use group 2A for the radio text.
*
* Group 56 contains the time (group 4A).
*
* All remaining groups use a filler group 15B block that just repeats
* the PI and PTY codes.
*/
void vivid_rds_generate(struct vivid_rds_gen *rds)
{
struct v4l2_rds_data *data = rds->data;
unsigned grp;
unsigned idx;
struct tm tm;
unsigned date;
unsigned time;
int l;
for (grp = 0; grp < VIVID_RDS_GEN_GROUPS; grp++, data += VIVID_RDS_GEN_BLKS_PER_GRP) {
data[0].lsb = rds->picode & 0xff;
data[0].msb = rds->picode >> 8;
data[0].block = V4L2_RDS_BLOCK_A | (V4L2_RDS_BLOCK_A << 3);
data[1].lsb = rds->pty << 5;
data[1].msb = (rds->pty >> 3) | (rds->tp << 2);
data[1].block = V4L2_RDS_BLOCK_B | (V4L2_RDS_BLOCK_B << 3);
data[3].block = V4L2_RDS_BLOCK_D | (V4L2_RDS_BLOCK_D << 3);
switch (grp) {
case 0 ... 3:
case 22 ... 25:
case 44 ... 47: /* Group 0B */
idx = (grp % 22) % 4;
data[1].lsb |= (rds->ta << 4) | (rds->ms << 3);
data[1].lsb |= vivid_get_di(rds, idx);
data[1].msb |= 1 << 3;
data[2].lsb = rds->picode & 0xff;
data[2].msb = rds->picode >> 8;
data[2].block = V4L2_RDS_BLOCK_C_ALT | (V4L2_RDS_BLOCK_C_ALT << 3);
data[3].lsb = rds->psname[2 * idx + 1];
data[3].msb = rds->psname[2 * idx];
break;
case 4 ... 19:
case 26 ... 41: /* Group 2A */
idx = ((grp - 4) % 22) % 16;
data[1].lsb |= idx;
data[1].msb |= 4 << 3;
data[2].msb = rds->radiotext[4 * idx];
data[2].lsb = rds->radiotext[4 * idx + 1];
data[2].block = V4L2_RDS_BLOCK_C | (V4L2_RDS_BLOCK_C << 3);
data[3].msb = rds->radiotext[4 * idx + 2];
data[3].lsb = rds->radiotext[4 * idx + 3];
break;
case 56:
/*
* Group 4A
*
* Uses the algorithm from Annex G of the RDS standard
* EN 50067:1998 to convert a UTC date to an RDS Modified
* Julian Day.
*/
time64_to_tm(ktime_get_real_seconds(), 0, &tm);
l = tm.tm_mon <= 1;
date = 14956 + tm.tm_mday + ((tm.tm_year - l) * 1461) / 4 +
((tm.tm_mon + 2 + l * 12) * 306001) / 10000;
time = (tm.tm_hour << 12) |
(tm.tm_min << 6) |
(sys_tz.tz_minuteswest >= 0 ? 0x20 : 0) |
(abs(sys_tz.tz_minuteswest) / 30);
data[1].lsb &= ~3;
data[1].lsb |= date >> 15;
data[1].msb |= 8 << 3;
data[2].lsb = (date << 1) & 0xfe;
data[2].lsb |= (time >> 16) & 1;
data[2].msb = (date >> 7) & 0xff;
data[2].block = V4L2_RDS_BLOCK_C | (V4L2_RDS_BLOCK_C << 3);
data[3].lsb = time & 0xff;
data[3].msb = (time >> 8) & 0xff;
break;
default: /* Group 15B */
data[1].lsb |= (rds->ta << 4) | (rds->ms << 3);
data[1].lsb |= vivid_get_di(rds, grp % 22);
data[1].msb |= 0x1f << 3;
data[2].lsb = rds->picode & 0xff;
data[2].msb = rds->picode >> 8;
data[2].block = V4L2_RDS_BLOCK_C_ALT | (V4L2_RDS_BLOCK_C_ALT << 3);
data[3].lsb = rds->pty << 5;
data[3].lsb |= (rds->ta << 4) | (rds->ms << 3);
data[3].lsb |= vivid_get_di(rds, grp % 22);
data[3].msb |= rds->pty >> 3;
data[3].msb |= 0x1f << 3;
break;
}
}
}
void vivid_rds_gen_fill(struct vivid_rds_gen *rds, unsigned freq,
bool alt)
{
/* Alternate PTY between Info and Weather */
if (rds->use_rbds) {
rds->picode = 0x2e75; /* 'KLNX' call sign */
rds->pty = alt ? 29 : 2;
} else {
rds->picode = 0x8088;
rds->pty = alt ? 16 : 3;
}
rds->mono_stereo = true;
rds->art_head = false;
rds->compressed = false;
rds->dyn_pty = false;
rds->tp = true;
rds->ta = alt;
rds->ms = true;
snprintf(rds->psname, sizeof(rds->psname), "%6d.%1d",
(freq / 16) % 1000000, (((freq & 0xf) * 10) / 16) % 10);
if (alt)
strscpy(rds->radiotext,
" The Radio Data System can switch between different Radio Texts ",
sizeof(rds->radiotext));
else
strscpy(rds->radiotext,
"An example of Radio Text as transmitted by the Radio Data System",
sizeof(rds->radiotext));
}
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